Investigation of radical locations in various sesame seeds by CW EPR and 9-GHz EPR imaging

Antioxidative and Anti-Inflammatory Phytochemicals and Related Stable Paramagnetic Species in Different Parts of Dragon Fruit

In this study, we investigated the antioxidant and anti-inflammatory phytochemicals and paramagnetic species in dragon fruit using high-performance liquid chromatography (HPLC) and electron paramagnetic resonance (EPR). HPLC analysis demonstrated that dragon fruit is enriched with bioactive phytochemicals, with significant variations between each part of the fruit. Anthocyanins namely, cyanidin 3-glucoside, delphinidin 3-glucoside, and pelargonidin 3-glucoside were detected in the dragon fruit peel and fresh red pulp. Epicatechin gallate, epigallocatechin, caffeine, and gallic acid were found in the dragon fruit seed. Additionally, 25–100 mg × L⁻¹ of dragon fruit pulp and peel extracts containing enrichment of cyanidin 3-glucoside were found to inhibit the production of reactive oxygen species (ROS), reactive nitrogen species (RNS), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) in cell-based studies without exerted cytotoxicity. EPR primarily detected two paramagnetic species in the red samples. These two different radical species were assigned as stable radicals and Mn²⁺ (paramagnetic species) based on the g-values and hyperfine components. In addition, the broad EPR line width of the white peel can be correlated to a unique moiety in dragon fruit. Our EPR and HPLC results provide new insight regarding the phytochemicals and related stable intermediates found in various parts of dragon fruit. Thus, we suggest here that there is the potential to use dragon fruit peel, which contains anthocyanins, as a natural active pharmaceutical ingredient.

EPR imaging of sinapyl alcohol and its application to the study of plant cell wall lignification

In bioimaging, bioorthogonal chemistry is most often used to visualize chemical reporters by fluorescence in their native environment. Herein, we show that TEMPO-based probes can be ligated to monolignol reporters by Diels-Alder chemistry in plant cell walls, paving the way for the study of lignification by EPR spectroscopy and imaging.

Detection of Antioxidant Phytochemicals Isolated from Camellia japonica Seeds Using HPLC and EPR Imaging

In this study, we investigated the formation of stable radicals and compounds related to antioxidants in Camellia japonica seeds using high performance liquid chromatography (HPLC) and X-band electron paramagnetic resonance imaging (EPRI). The C. japonica seed coat extracts exhibited antioxidant activity in both in vitro and cell-based studies. The extracts inhibited reactive oxygen and reactive nitrogen species production in cell-based studies. HPLC chromatograms indicated that hydrophilic antioxidant compounds—namely, gallic acid, gallocatechin, epigallocatechin, caffeine, catechin, epicatechin, and epicatechin gallate—were found in the methanolic extract. Lipophilic antioxidant compounds—including α-tocopherol, γ-tocopherol, β-tocopherol, δ-tocopherol, α-tocotrienol, γ-tocotrienol, and δ-tocotrienol—were found in the hexane extract. EPRI primarily detected paramagnetic species in seed coats. These radical species were stable organic radicals based on the peak-to-peak line width and g-values. The signals from these stable radicals were strong and stable with a g-value of 2.002. Noninvasive EPRI of the radicals present in C. japonica seeds indicated that the stable radicals were essentially located in the seed coats. The EPRI of the cotyledon demonstrated that additional radicals were localized at an apex of the cotyledon. The results indicated that the stable radicals detected by EPRI and the hydrophilic and lipophilic antioxidant compounds analyzed by HPLC were related to antioxidant reactants and products.

Free Radical Scavenging Capability of Various Defatted Sesame Seed Cakes and Hulls Using EPR Compared with In Vitro Testing and HPLC Analysis

The free radical scavenging activities of black and white sesame seed hulls and the powder of black and white sesame seed cakes were investigated using noninvasive continuous wave electron paramagnetic resonance (EPR) and antioxidant assays. With black sesame seed hulls and the powder of black sesame seed cakes, EPR detected the very strong single-line signal intensities that correspond to the stable organic radicals, while the spectrum of the white sesame seed hulls and the white sesame seed cakes showed no signal. The in vitro antioxidant activities of black and white sesame seed cake extract were evaluated by DPPH free radical scavenging activity, hydrogen peroxide scavenging activity, and ferric reducing antioxidant power (FRAP) assay. The results indicated that the extract from black sesame seed cake possessed a greater DPPH radical inhibitory activity and hydrogen peroxide inhibitory activity than white sesame seed cake extract, with IC₅₀ values of 0.847 ± 0.011 mg/mL and 0.338 ± 0.007 mg/mL, respectively. Black sesame seed cake extract also showed a strong reducing power with a FRAP value of 1.307 ± 0.037 mM Fe (II)/g of extract weight and an EC₁ value of 0.683 ± 0.002 mg/mL. The main compounds from the black and white sesame seed cake extracts were analysed using high-performance liquid chromatography (HPLC). The results revealed that the main compounds in black and white sesame seed cake extracts were in a group of water-soluble lignans, mainly sesaminol triglucoside and sesaminol diglucoside. However, sesaminol diglucoside was found in large amounts in the black sesame seed cake extract, while it was found in a very small amount in the white sesame seed cake extract. Therefore, these results demonstrated considerable antioxidant capacity of the sesame seed, especially in the black strain.

Investigation of Pigments in Thai Purple Rice Using Electron Paramagnetic Resonance Imaging and HPLC

Paramagnetic species (radicals) related pigments in Thai purple rice were investigated by electron paramagnetic resonance (EPR), X-band (9 GHz) EPR imaging (EPRI), and HPLC. The location and distribution of the paramagnetic species in purple and white rice were determined by EPR and EPRI. EPR primarily detected three paramagnetic species in purple rice, which were identified as organic radicals, Mn²⁺, and Fe³⁺ based on the g-values and hyperfine components of the EPR signals. Noninvasive two-dimensional (2D) EPRI revealed that these stable radicals are primarily located in the pigmented region of purple rice, while very few radicals were observed in the interior of the rice. HPLC revealed that the major compounds were cyanidin-3-O-glucoside and peonidin-3-O-glucoside. EPR, EPR imaging, and HPLC results indicate that the stable radicals contain the radical state of anthocyanins and are mostly found within the pigmented embryo region of purple rice. They could be either associated with antioxidant activities or could be one of the products of their oxidative decomposition.

Wheat seed ageing viewed through the cellular redox environment and changes in pH

To elucidate biochemical mechanisms leading to seed deterioration, we studied 23 wheat genotypes after exposure to seed bank storage for 6-16 years compared to controlled deterioration (CD) at 45 °C and 14 (CD14) and 18% (CD18) moisture content (MC) for up to 32 days. Under two seed bank storage conditions, seed viability was maintained in cold storage (CS) at 0 °C and 9% seed MC, but significantly decreased in ambient storage (AS) at 20 °C and 9% MC. Under AS and CS, organic free radicals, most likely semiquinones, accumulated, detected by electron paramagnetic resonance, while the antioxidant glutathione (GSH) was partly lost and partly converted to glutathione disulphide (GSSG), detected by HPLC. Under AS the glutathione half-cell reduction potential (E_GSSG/2GSH) shifted towards more oxidising conditions, from -186 to -141 mV. In seeds exposed to CD14 or CD18, no accumulation of organic free radicals was observed, GSH and seed viability declined within 32 and 7 days, respectively, GSSG hardly changed (CD14) or decreased (CD18) and E_GSSG/2GSH shifted to -116 mV. The pH of extracts prepared from seeds subjected to CS, AS and CD14 decreased with viability, and remained high under CD18. Across all treatments, E_GSSG/2GSH correlated significantly with seed viability (r = 0.8, p<.001). Data are discussed with a view that the cytoplasm is in a glassy state in CS and AS, but during the CD treatments, underwent transition to a liquid state. We suggest that enzymes can be active during CD but not under the seed bank conditions tested. However, upon CD, enzyme-based repair processes were apparently outweighed by deteriorative reactions. We conclude that seed ageing by CD and under seed bank conditions are accompanied by different biochemical reactions.

EPR and HPLC Investigation of Pigments in Thai Purple Rice

We investigated the pigments in Thai purple rice using electron paramagnetic resonance (EPR), X-band (9 GHz) EPR imaging (EPRI), and HPLC. The location and spatial distribution of the paramagnetic species in purple and white rice were determined by EPR and EPRI. EPR primarily detected three paramagnetic species in purple rice, which were identified as stable radicals, Mn²⁺, and Fe³⁺ based on the gvalues and hyperfine components of the EPR signals. Subsequent noninvasive two-dimensional (2D) EPRI revealed that these stable radicals are primarily located in the pigmented region of purple rice, while very few radicals were observed in the interior of the rice. HPLC revealed that the major compounds were cyanidin-3-O-glucoside and peonidin-3-O-glucoside. Scavenging activities, EPR, and EPR imaging results indicate that the stable radicals contain the radical state of anthocyanins and are mostly found within the pigmented embryo region of purple rice. They could be either associated with scavenging activities or could be one of the products of their oxidative decomposition.

X-band Electron Paramagnetic Resonance Investigation of Stable Organic Radicals Present under Cold Stratification in 'Fuji' Apple Seeds

We investigated stable organic radicals formed in response to cold stratification in 'Fuji' apple seeds using X-band (9 GHz) electron paramagnetic resonance (EPR) technique. This technique primarily detected two paramagnetic species in each seed. These two different radical species were assigned as a stable organic radical and Mn²⁺ species based on the g values and hyperfine components. Signal from the stable radicals was noted at a g value of about 2.00 and was strong and relatively stable. Significant radical intensity changes were observed in apple seeds on refrigeration along with water supplementation. The strongest radical intensity and a very weak Mn²⁺ signal were also observed for the seeds kept in moisture-containing sand in a refrigerator. Noninvasive EPR of the radicals present in each seed revealed that the stable radicals were located primarily in the seed coat. These results indicate that the significant radical intensity changes in apple seeds under refrigeration for at least 90 days followed by water supplementation for one week, can be related to cold stratification of the seeds.

Investigating Pigment Radicals in Black Rice Using HPLC and Multi-EPR

We investigated the location and distribution of paramagnetic species in black and white rice using electron paramagnetic resonance (EPR), X-band (9 GHz) EPR imaging (EPRI), and HPLC. EPR primarily detected two paramagnetic species in black rice, which were identified as a stable radical and Mn²⁺ species, based on the g values and hyperfine components of the EPR signals. The signal from the stable radical appeared at g ≈ 2.00 and was relatively strong and stable. Subsequent noninvasive two-dimensional (2D) EPRI revealed that this stable radical was primarily located in the pigmented region of black rice, while very few radicals were observed in the rice interior. Pigments extracted from black rice were analyzed using HPLC; the major compound was found to be cyanidin-3-glucoside. EPR and HPLC results indicate that the stable radical was only found within the pigmented region of the rice, and that it could either be cyanidin-3-glucoside, or one of its oxidative decomposition products.

Investigation of scavenging activities and distribution of paramagnetic species in Zanthoxylum limonella seeds

We investigated the scavenging activities of methanol-extracted oil and the distribution of paramagnetic species in Zanthoxylum limonella (ZL) seeds using noninvasive 9 GHz electron paramagnetic resonance (EPR) imaging and continuous wave EPR. EPR detected three different stable paramagnetic species that were assigned to stable organic radicals, Mn²⁺, and other paramagnetic metal complexes. Two-dimensional EPR imaging showed that the stable paramagnetic species were located in the pigmented seed region with a strong intensity. Gas chromatography-mass spectrophotometric (GC-MS) analyses were then performed to identify the compound possibly related to the scavenging activity. The DPPH scavenging activities of ZL were slightly higher than those of Piper nigrum and Coriandrum sativum. Based on the results of EPR, GC-MS, and other methods, limonene in ZL is one of the major compounds that can be related to the scavenging activities.

Investigating the Distribution of Stable Paramagnetic Species in an Apple Seed Using X-Band EPR and EPR Imaging

This study investigated the location and distribution of paramagnetic species in apple seeds using electron paramagnetic resonance (EPR) and X-band (9 GHz) EPR imaging (EPRI). EPR primarily detected two paramagnetic species per measured seed. These two different radical species were assigned as stable radicals and Mn²⁺ species based on the g values and hyperfine components. The signal from the stable radical was noted at g ≈ 2.00 and was strong and relatively stable. The subsequent noninvasive EPRI of the radical present in each seed revealed that the stable radicals were located primarily in the seed coat, with very few radicals observed in the cotyledon of the seed. These results indicate that the stable radical species were only found within the seed coat, and few radical species were found in other seed parts.

EPR imaging and HPLC characterization of the pigment-based organic free radical in black soybean seeds

We investigated the location and distribution of paramagnetic species in dry black, brown, and yellow (normal) soybean seeds using electron paramagnetic resonance (EPR), X-band (9 GHz) EPR imaging (EPRI), and HPLC. EPR primarily detected two paramagnetic species in black soybean. These two different radical species were assigned as stable organic radical and Mn2+ species based on the g values and hyperfine structures. The signal from the stable radical was noted at g ≈ 2.00 and was relatively strong and stable. Subsequent noninvasive two-dimensional (2D) EPRI of the radical present in black soybean revealed that the stable radical was primarily located in the pigmented region of the soybean coat, with very few radicals observed in the soybean cotyledon (interior). Pigments extracted from black soybean were analyzed using HPLC. The major compound was found to be cyanidin-3-glucoside. Multi-EPR and HPLC results indicate that the stable radical was only found within the pigmented region of the soybean coat, and it could be cyanidin-3-glucoside or an oxidative decomposition product.